Since the invention of vacuum packing and plastic film packaging, the food preparation industry has grown in leaps and bounds regarding the variety of products that can be offered to consumers. Prior to this, food marketing was very limited due to food spoilage, and limited the variety of forms products could be presented. For example, a customer ordered the butcher to slice cold cuts or meats rather than purchasing presliced meats from a grocery's refrigeration section. One was also limited to the types of food products available. Modern methods of packaging have greatly extended the life of these products, and some remain fresh for weeks and months under refrigeration. With the modernization of these packaging techniques, the machinery has also changed tremendously.
The first type of machinery built to perform such packaging was the "Die-Train" machine. In this machine, a multitude of metal molds or dies move in circular motion, similar to a conveyer belt, across the various work stations, where different operations are performed. Each film-pack remains in its mold until the final station, when the circuit of molds returns to the beginning of the machine, and the products exits the system. The drawback to this machine is when a different product is desired and all of the several dozen molds have to be removed and replaced with the molds.
A later type, which is more frequently used, is the "Die-Less" machine. As the name implies, this machine operates without cycling a plurality of dies in the circuit of the machine, but rather indexes the plastic tray-film along the work stations of the machine, and simply moving the molds and vacuuming apparatus up to the film at each station, as required. Thus, only one master molding-tool is required at each station. Such a prior-art machine is that manufactured by Tiromat, which is a die-less packing machine. At the beginning of the cycle of this machine, the plastic film is unwound onto the machine in advance of the "forming station". At the forming station, the tooling rises and heats plastic film to make it deformable. A vacuum is then created to suck the soft film into the mold, thus assuming the form desired for the package for the given product. The tooling is then lowered out of the way, and the film advanced to the next station, which is the loading station, where the product is loaded into the packages. either manually or by automated equipment. The next station is the sealing station. Here, the tooling rises and surrounds the package in an enclosed chamber to which is then applied a vacuum, removing all air from the entire chamber to form the final product, after which the upper film is lowered over the product and heat-sealed along the perimeter of the package. The vacuum is then vented, the tooling lowered, and the machine indexed again. Cutter knives cut the connected packages into the individual product packages.
As in all industrial settings, there is the continual desire to make the given process faster, cheaper, and more efficient. This is not, of course, as easy as installing a faster motor. Motor speed is already a parameter limited by the avoidance of "machine jerk" (too sudden acceleration of film movement causing various operational disorders such as the spilling of the product out of the package). Also, overall speed is limited by the rate at which the tooling rises and lowers, and the time required for the tooling to do its job at each of the respective stations.
Another place one might look to increase productivity is at the tooling stations. The prior art machines are multiple mold units, usually with several molds along the width of the machine, and, frequently, with a plurality of such rows. For example, four balognas would fit widthwise along the machine, and with two such rows, for a total of eight units. This would amount to eight packages of product being produced in each cycle or index of the machine operation. Therefore, in order to optimize machine efficiency, one might think that it is as simple as increasing the size of the master mold: make instead of two rows of four, in this example, five rows, for a total of twenty units per index, and thusly, increase the productivity by 150%. But this is entirely unfeasible. Such a mold would weigh nearly 300 pounds. The present machine element for raising and lowering the tools would be insufficient. To install a larger apparatus would not solve the problem, as the speed of the movement of the tooling would suffer, canceling out the gain in products per cycle. In addition, there is the requirement that the molds be interchangeable. This is necessary in that the same machines are used for a multitude of different products. When a run of bologna, for example, is finished, packages of beef stick, for example, may be run, which is simply accomplished by removing the mold with bologna-package-shaped mold and replacing it with the beef-stick-mold. However, a 300 pound mold is altogether too unwiedly to be used in this manner.